The present invention is concerned with thermoplastic poly bibenzyl sulfone polymers and copolymers containing recurring bibenzyl sulfone groups in the polymer molecule, said polymers and copolymers exhibiting high temperature stability and improved tensile properties as compared with conventional aromatic sulfone polymers.
There are a number of polymers available today which offer extremely good resistance to heat at temperatures in excess of 100.degree. C, good electrical properties and are relatively inert to attack by chemical solvents. Among these materials are the polyphenylene oxides, polysulfones, polysulfonates, polysulfone polyesters, polysulfonamides and like materials. These polymers are generally characterized by recurring phenyl or biphenyl groups joined together by sulfur, oxygen, sulfone, amide or bivalent hydrocarbon radicals.
One commercially available polysulfone is produced by the reaction between the sodium salt of 2,2 bis (4-hydroxy phenol) propane and 4,4'-dichlorodiphenyl sulfone. This material is characterized as being stable in air at temperatures in excess of 300.degree. F and is fairly rigid, exhibiting a flexural modulus of elasticity of nearly 400,000 psi at room temperature. Another class of polysulfone polymers are the polyaryl sulfones such as, for example, disclosed in British patent specification No. 1,122,192. These polymers are amorphous and consist mainly of phenyl and biphenyl groups linked by thermally stable ether and sulfone groups, and may be distinguished from polysulfones mentioned above by the absence of aliphatic groups. The molding grade polyaryl sulfones may be processed by injection molding or extrusion techniques, but extremely high temperatures are required. For example, the cylinder and nozzle of an injection molding machine must normally be equipped to reach temperatures of 800.degree. F., and temperatures in the range of about 600.degree. to 750.degree. F. are required for extrusion. Other polyaryl sulfones exhibiting similar properties are taught in British patent specification No. 1,166,624 in which polymers having a diphenyl ether sulfone repeating unit in the polymer chain are prepared, and British patent specification No. 1,060,546 in which sulfone copolymers containing diphenyl ether sulfone and at least one other aromatic sulfone such as biphenyl, diphenyl methane or naphthalene are prepared.
Whereas the above and other sulfone polymers have filled a long felt need for thermoplastic materials which do not degrade at temperatures in excess of 100.degree. C. and in many cases at temperatures up to about 500.degree. C., their thermal characteristics are such that extremely high temperatures are required to process them. This in turn may require the use of special or modified processing equipment adapted for high temperatures and the consumption of large amounts of energy.
Accordingly, it is an object of this invention to provide aromatic sulfone polymers which exhibit toughness, flexibility, high temperature stability, good tensile stress properties, a relatively high heat distortion temperature, and good dielectric properties.
Another object of this invention is to provide a novel monomer suitable for the preparation of sulfone polymers and copolymers.
Still another object is to provide aromatic sulfone homopolymers and copolymers containing bibenzyl sulfone units which exhibit superior tensile stress and processing properties.